Currently, Micro-Electro-Mechanical Systems (MEMS) is a known technology. However, as its structure suffers from issues which are difficult to be overcome in the course of commercialized application, research on its commercialized application is still being conducted continually.
FIGS. 1-1 and 1-2 illustrate an operationally basic principle, where a telescopic pixel 108 is adopted, and the pixel 108 comprises a transparent indium tin oxide (ITO) electrode 107, a glass 104, a first mirror (hanging thin film) 105 and a second mirror 106. In the state as shown in FIG. 1-1, a parallel, background light 103 emitted from left to right by a backlight source passes through the glass 104, but may not be transmitted by the first mirror (hanging thin film) 105 and the second mirror 106 which are disposed on a display device so as to be reflected. Accordingly, as seen by a viewer 101, what is shown on a screen 102 is a black picture. While in the state as shown in FIG. 1-2, the setting of the second mirror 106 remains the same, but a voltage is applied to the first mirror (hanging thin film) 105 to make it deflected. Accordingly, reflected light with a deflection angle will be formed when the parallel background light 103 from the backlight source irradiates onto the first mirror 105. The reflected light exits through pixels after it has been reflected secondarily by the second mirror 106, so as to be captured by the viewer 101. Thus, an object of displaying by use of projective light is realized.
A MEMS display scheme based on the above technical principle has been suggested many times, but hitherto, it has not been applied in the sense of batch production for commercialization successfully. The main reason is that, in terms of electrode formation, the formation process of a MEMS structure has high difficulty, a low productivity and an expensive production cost. Therefore, it is difficult to produce it in batches for commercialization.
Regarding a liquid crystal lens (LC lens), whose optical characteristics are similar to those of a liquid crystal display, liquid crystals are filled between panels formed with electrodes, and are driven in accordance with an externally applied voltage to make a path difference being produced between light transmitted through the liquid crystals, thereby causing its focal length f to change. More specifically, as shown in FIG. 2, k is the focal length f, and k(x) denotes a diagonal distance for f, the diagonal distance being a diagonal length which is determined according to f and a vertical distance x; an angle γ is a function relating to a space distance of an anchoring energy W(x), an applied voltage V and a cell gap d, which is similar to insulation property, elasticity and optical constants of liquid crystals. With respect to a certain liquid crystal, the angle γ can be defined as follows:
            γ      ⁡              (                              W            ⁡                          (              x              )                                ·          V          ·          d                )              =          arctan      (              x        f            )        ,Wherein, f is the focal length of a lens, and when a constant V is applied to a liquid crystal unit as the lens and d and f are constant, the space distance of the anchoring energy W(x) can be calculated from the above formula. In addition, applying a different voltage V can change the focal length f. Research on how to evaluate potential abilities of the adjustable liquid crystal lens is currently being conducted continually.
In a publicly issued document “SID 2008: A Liquid Crystal Lens with Non-uniform Anchoring Energy”, an example in which a liquid crystal lens is adopted is provided. The liquid crystal lens is disposed between two glass substrates, and a structure of liquid crystal display is formed on the structure of the liquid crystal lens having liquid crystals placed therein, so as to attain a display effect of three-dimensional image. Here, the liquid crystal lens functions as a concave lens and a convex lens in accordance with an electrode structure within the substrates, an alignment of liquid crystals and an externally applied voltage.
Furthermore, in a publicly issued document “SID 2008: 25.3: Autostereoscopic 2D/3D Switching Display Using Electric-Field-Driven LC Lens (ELC Lens)”, two methods for adjusting a focal length by applying an electric field are provided. As shown in FIGS. 3-1 and 3-2, in the states of turning-on and -off of a switch, respectively, on/off states of light transmitted through the lens are driven by a change of a liquid crystal convex lens based on a convex structure; while regarding FIGS. 3-3 and 3-4, in the states of turning-on and -off of the switch, they are driven by a polarization switch based on an anisotropic lens.
As seen from above, in the current technical environment, it has brought about concern of more and more research subjects how to achieve an object of projecting light, through adjustment of a focal distance of a liquid crystal lens by means of changing an externally applied voltage, and directional adjustment of light using structure of the liquid crystal lens and the reflection principle, in a MEMS structure.